In: Statistics and Probability
At a local store, 65 female employees were randomly selected and
it was found that their mean monthly
income was $625 with a standard deviation of $121.50. Seventy-five
male employees were also randomly
selected and their mean monthly income was found to be $667 with a
standard deviation of $168.70. Test the
hypothesis that male employees have a higher monthly income than
female employees. Use α = 0.01.
Use any method, however, follow the PHANTOMS acronym.
P - Parameter Statement
H - Hypotheses
A - Assumptions & Conditions
N - Name the Test and state the curve you're using
T - Test Statistic - Round your value to TWO decimals and state the command you used to find this value
O - Obtain the P-Value or Critical Value . State the command you are using to find these values
M - Make a Decision about the Null Hypothesis and explain why
S - State Your Conclusion About the Claim
P- male employees have a higher monthly income than female employees.
H-
Ho :   µ1 - µ2 =   0
Ha :   µ1-µ2 <   0
A-
population is normally distributed
Sample are random and independent
N- 2 independent sample t test
T-
Sample #1   ---->   1  
       
mean of sample 1,    x̅1=   625.00  
       
standard deviation of sample 1,   s1 =   
121.5          
size of sample 1,    n1=   65  
       
          
       
Sample #2   ---->   2  
       
mean of sample 2,    x̅2=   667.000  
       
standard deviation of sample 2,   s2 =   
168.70          
size of sample 2,    n2=   75  
       
          
       
difference in sample means = x̅1-x̅2 =   
625.000   -   667.0000  
=   -42.0000
          
       
std error , SE =    √(s1²/n1+s2²/n2) =   
24.6287          
t-statistic = ((x̅1-x̅2)-µd)/SE = (  
-42.0000   /   24.6287   )
=   -1.7053
O-
DF=133
p-value =        0.04523   [
excel function: =T.DIST(t stat,df) ]
M-
Conclusion:     p-value>α , Do not reject null
hypothesis  
      
S- There is not enough evidence to conclude that male employees have a higher monthly income than female employees.
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